Damage Tolerance: Is it Important to You?

One main topic in composites is “damage tolerance”. Physical testing of wind turbine blades is such an expensive proposition that virtual testing is needed as much as possible – to this end, small-scale flaw testing on a materials testing system is extremely helpful to understand and predict how the larger system will behave in service…

It is a pretty well-known fact that composite turbine blades, when made by hand, will at some place or another, likely include a flaw; by making “simulated flaws” in laboratory specimens, the testing system allows the operator to understand what to expect from these flaws – fatigue crack growth – in a biaxial state (stresses in 2 directions) under extreme conditions (high/low temperature presumably). This information is then passed onto the modeling world, where full scale CAD/FEA models can be used for “virtual testing” at much lower cost than physical testing – to see what happens to the overall structure under certain conditions.

So the idea is not so much to point to flaws that cause failures, but to understand how flaws behave under various loading conditions – as input to the Finite Element Analysis (FEA) model.